Due to proposals such as a cloud system, there is an increasing demand for a datacenter containing a large number of servers. Since a server consumes a large amount of current, it generates heat. Thus, a cooling system for cooling the large number of servers together is needed. As an example of such a cooling system, a system has been proposed in which a hot zone and a cold zone are provided in a casing; and a server rack is disposed on a boundary therebetween so that cold air from the cold zone cools the server rack, warm air generated due to heat exchange is cooled by a cooler in the hot zone, and the cooled air is supplied to the cold zone again (Patent Literature 1).
When such a cooling system is employed, servers are packed in each casing. The system may have various advantages as follows: by employing a container type casing, the shipping thereof can be made easier; since each unit is optimally designed beforehand, its energy conservation ability is excellent; speedy construction of a datacenter and early start of its operation can be realized only by disposing a plurality of casings side by side; and an outdoor type datacenter can be constructed.